The present invention relates to an optimum-recording-speed determining method for determining whether or not a given recording speed to be used for optical disk recording achieves appropriate recording that permits reproduction of recorded information with minimized reading errors or which recording speed permits reproduction of recorded information with minimized reading errors, and a recording-speed setting method and optical disk recording method based on such an optimum-recording-speed determination.
Today, recording on writable optical disks, such as write-once optical disks like CDxe2x88x92R and DVDxe2x88x92R media and rewritable optical disks like DVD+RW and DVDxe2x88x92RW media, is performed at increased speeds relative to a normal (non-increased or one-time) reproducing speed, such as a double speed, quadruple speed and the like, with a view to reducing a necessary recording time.
For appropriate optical disk recording that permits subsequent reproduction of recorded information with minimized reading errors, it has been conventional to change the so-called xe2x80x9crecording strategyxe2x80x9d such as by adjusting a power level, irradiation time, irradiation timing, etc. of a recording laser light beam in accordance with a selected one of the recording speed increase ratios.
Recently, it has been found that as the recording speed increase ratio is raised, appropriate recording tends to become more difficult to achieve by just changing the recording strategy (e.g., adjusting the power level, irradiation time, irradiation timing, etc. of the recording laser light beam), even with a same type of media (optical disks), depending on the manufacturer of the media, and thus there would be manufactured media prone to frequently cause reading errors. Consequently, it has been found that even recording speeds, settable in a recording drive (i.e., optical disk recording apparatus), have to be properly restricted depending on the media used.
In view of the foregoing, it is an object of the present invention to provide an optimum-recording-speed determining method for determining whether or not a recording speed to be used for optical disk recording achieves appropriate recording that permits reproduction of recorded information with minimized reading errors or which recording speed permits reproduction of recorded information with minimized reading errors, and an improved recording-speed setting method and optical disk recording method based on such an optimum-recording-speed determination.
According to an aspect of the present invention, there is provided a method of determining an optimum recording speed of an optical disk, which comprises the steps of: performing test recording on the optical disk at a given recording speed while changing a recording laser power level, and reproducing results of the test recording from the optical disk; measuring parameter values pertaining to reproduced signal quality on the basis of the reproduced results; and determining, on the basis of the parameter values, whether there is achieved any laser power level that can provide reproduced signal quality falling within a predetermined acceptable range, When it is determined that there is achieved the laser power level that can provide reproduced signal quality falling within the predetermined acceptable range, the given recording speed is judged as a proper recording speed, while when it is determined that there is achieved no laser power level that can provide reproduced signal quality falling within the predetermined acceptable range, the given recording speed is judged as an improper recording speed. With such arrangements, a determination can be made as to whether or not the recording speed to be used provides for appropriate recording that permits reproduction of recorded information with minimized reading errors.
According to another aspect of the present invention, there is provided a method of determining an optimum recording speed of an optical disk, which comprises the steps of: performing test recording on the optical disk while changing a recording speed and a recording laser power level, and reproducing results of the test recording from the optical disk; measuring parameter values pertaining to reproduced signal quality on the basis of the reproduced results; and determining, on the basis of the parameter values, whether there is achieved any laser power level that can provide reproduced signal quality falling within a predetermined acceptable range. Recording speed achieving the laser power level that can provide reproduced signal quality falling within the predetermined acceptable range is judged as a proper recording speed, while another recording speed achieving no laser power level that can provide reproduced signal quality falling within the predetermined acceptable range is judged as an improper recording speed.
The above-mentioned parameter values pertaining to reproduced signal quality may include at least parameter values relating to the total number of synchronization signals detected within a predetermined time period and a ratio between top and bottom peaks of a reproduced HF signal. Here, a recording speed achieving a laser power level that allows both of the parameter values relating to the total number of detected synchronization signals and the ratio between top and bottom peaks to fall within respective acceptable ranges may be judged as a proper recording speed. Results of the judgement may be displayed visually. Even at a recording speed which allows the optical disk recording apparatus to perform appropriate recording that permits reproduction of recorded information with minimized reading errors, a buffer memory within the recording apparatus, during actual recording, would cause a buffer underrun condition, i.e., run out of data, if a host computer, such as a personal computer, has low processing capabilities and can only transmit recording data at a low rate, with the result that the optical disk recording apparatus fails in the recording. To avoid such inconveniences, it is preferred that the optimum recording-speed determining method of the invention further comprise the steps of: causing the recording data to be transferred from a host computer to an optical disk recording apparatus so that the optical disk recording apparatus records the recording data onto the optical disk with a reproducing laser power level while changing the recording speed within a recording speed range settable in the optical disk recording apparatus; determining whether the buffer memory of the optical disk recording apparatus will cause buffer underrun during recording of the recording data, to thereby identify one or more recording speeds that can avoid the buffer underrun; and then performing the test recording by use of one of the recording speeds that can avoid the buffer underrun.
According to still another aspect of the present invention, there is provided a method of setting a recording speed of an optical disk, in which one or more recording speeds judged as proper through any one of the above-described speed determining methods is displayed in such a manner that one of the displayed recording speeds can be set for use in actual recording on the basis of a speed designating operation by a user.
According to still another aspect of the present invention, there is provided a method of setting a recording speed of an optical disk, in which one or more recording speeds judged as proper through any one of the speed determining methods is stored onto a predetermined area of the optical disk, and in which as the optical disk is re-loaded into the optical disk recording apparatus, information indicative of the recording speeds judged as proper is read out from the predetermined area and displayed in such a manner that one of the displayed recording speeds can be set for use in actual recording on the basis of a speed designating operation by a user without a need for performing the test recording again. Thus, for an optical disk for which the optimum recording speed determination has been performed once, the optimum recording speed can be known without having to perform the optimum recording speed determination again, with the result that a time necessary for making preparations for actual recording can be reduced to a significant degree.
According to still another aspect of the present invention, there is provided a method of setting a recording speed of an optical disk, which comprises: a step of performing test recording on the optical disk with a recording speed initially set to a maximum available speed while changing a recording laser power level, and reproducing results of the test recording from the optical disk; a step of measuring parameter values pertaining to reproduced signal quality on the basis of the reproduced results; a step of, when there is achieved a recording laser power level that can provide reproduced signal quality higher than a predetermined value, terminating the test recording at the recording speed, but when there is achieved no recording laser power level that can provide reproduced signal quality higher than the predetermined value, performing the test recording while sequentially lowering the recording speed and terminating the test recording at a recording speed that can provide reproduced signal quality higher than the predetermined value; and a step of displaying, as a recommendable or settable recording speed, each recording speed having been used at the time of termination of the test recording in such a manner that the displayed recording speed can be set for use in actual recording. In this invention, the recording can be performed at a highest one of such recording speeds that provide for appropriate recording capable of minimizing reading errors during reproduction of recorded information. This recording-speed setting method may further comprise the steps of: causing recording data to be transferred from a host computer to an optical disk recording apparatus so that the optical disk recording apparatus records the recording data onto the optical disk with a reproducing laser power level while changing a recording speed within a recording speed range settable in the optical disk recording apparatus; determining whether a buffer memory of the optical disk recording apparatus will cause buffer underrun during recording of the recording data, to thereby identify one or more recording speeds that can avoid the buffer underrun; and setting a highest one of the one or more recording speeds as the maximum available speed for performing the test recording. With such arrangements, the present invention can effectively avoid needlessly or wastefully performing the test recording for recording speeds that would cause the buffer underrun problem. Further, a warning may be displayed when it has been determined, as a result of the test recording at the maximum available speed, that there is achieved no recording laser power level that can provide reproduced signal quality higher than the predetermined value, so that the user can be informed that no recording is permitted at that the maximum available speed.
According to still another aspect of the present invention, there is provided a method of setting a recording speed of an optical disk, which comprises: a step of performing test recording on the optical disk with a recording speed initially set to a desired speed designated by a user operation while changing a recording laser power level, and reproducing results of the test recording from the optical disk; a step of measuring parameter values pertaining to reproduced signal quality on the basis of the reproduced results; a step of, when there is achieved a recording laser power level that can provide reproduced signal quality higher than a predetermined value, terminating the test recording at the recording speed, but when there is achieved no recording laser power level that can provide reproduced signal quality higher than the predetermined value, performing the test recording while sequentially lowering the recording speed and terminating the test recording at a recording speed that can provide reproduced signal quality higher than the predetermined value; and a step of displaying, as a recommendable or settable recording speed, each recording speed having been used at the time of termination of the test recording in such a manner that the displayed recording speed can be set for use in actual recording. With such arrangements, the recording can be performed at a highest one of the recording speeds within the user-designated speed range that provide for appropriate recording capable of minimizing reading errors during reproduction of recorded information. This recording-speed setting method too may further comprise the steps of: causing recording data to be transferred from a host computer to an optical disk recording apparatus so that the optical disk recording apparatus records the recording data onto the optical disk with a reproducing laser power level while changing a recording speed within a recording speed range settable in the optical disk recording apparatus; and determining whether a buffer memory of the optical disk recording apparatus will cause buffer underrun during recording of the recording data, to thereby identify one or more recording speeds that can avoid the buffer underrun. In this invention, the user is allowed to designate an initial recording speed for the test recording from among the recording speeds that can avoid the buffer underrun. With such arrangements, the present invention can effectively avoid needlessly or wastefully performing the test recording for recording speeds that would cause the buffer underrun problem. Further, a warning may be displayed when it has been determined, as a result of the test recording at the user-designated speed, that there is achieved no recording laser power level that can provide reproduced signal quality higher than the predetermined value, so as to inform the user that no recording is permitted at that the maximum available speed and thereby prompt the user to change the setting of the recording speed.
According to still another aspect of the present invention, there is provided an optical disk recording method, in which actual recording is performed on an optical disk at a recording speed that has been set for use in the actual recording through any one of the above-described recording speed setting methods, by, on the basis of the test recording, setting the recording laser power level to a value with which there has been provided reproduced signal quality within the predetermined acceptable range. Such arrangements, recording can be performed on the optical disk at a high speed in such a manner as to minimize reading errors.